Guess I lucked out after all! I took the current strut with me to my local autozone. He went and got the one he had and took it out of the package. He placed one end on the counter and was able to push it closed. Now. I had already tried mine at home with no success, but I really laid in it this time, and it closed! So I went home and reinstalled my old one, but positioned myself for maximum leverage without (hopefully) breaking the plywood. I gave it a hard shove, and it closed! So I'm all buttoned up and back in business!
So, I owe the design engineer an apology …
I keep a bottle of ketchup handy, for occasions like this when I have to eat crow!